Assessment of duplex coating combining plasma electrolytic oxidation and polymer layer on AZ31 magnesium alloy

► Mechanical and corrosion properties of polymer-coated AZ31 alloy are investigated. ► PEO and a fluorotitanate-zirconate pre-treatment are compared. ► Ti/Zr + polymer coating shows better impact resistance than the PEO + polymer system. ► PEO + polymer provides higher corrosion resistance than Ti/Zr + polymer coating. ► Corrosion properties of polymer coatings are rapidly evaluated by the ac/dc/ac test.